In a recent development for completions in open hole into depths where pressures can be 15,000 PSIG or more it has been desirable to facilitate the advancement of the completion to the desired depth with the aid of circulation. In such completions the bottom hole assembly can contain screens from production from a given zone while the borehole may continue further into another zone that can produce higher pressures. To date the available pressure rating of shoe track equipment is only in the realm of about 5,000 PSIG. At the same time regulations have been made stricter regarding dual isolators for the high pressure zones. One of the risks for known float shoes that are used to aid circulation when running in is that the check valves in such a shoe will experience differential pressure from a high pressure formation below the producing formation where the screens are located so as to fail. For that reason the dual check valves in such float shoes cannot be considered under the regulations as effective dual isolation devices. One expensive way in the past to cope with this issue is to essentially cement in place the length of the shoe track in the annular space and internally. Such a procedure is not only expensive but presents concerns of reliability of the seal that is obtained.
Dual flappers are illustrated in U.S. Pat. No. 8,424,611; US 2014/0238697 (FIG. 12) and U.S. Pat. No. 6,394,187.
The present invention seeks to address this problem in a functionally effective and economical way. The producing zone is externally isolated just above the shoe track. The wash pipe that goes through the screen assembly extends through a packer and down to a lower flapper to push a sleeve to hold the lower flapper open. This allows circulation when running in. Once having reached the desired depth with the screens an isolation packer such as a swell packer begins to swell to close off the annulus against the open hole to prevent fluids from further downhole from migrating up to the screens adjacent the producing zone. Within the shoe track, the high pressure rated packer is set against the inside wall. The wash pipe is picked up to allow the lower flapper to close. This flapper is oriented to prevent flow from coming uphole. The lower flapper is disposed below the high pressure isolation packer. Further removal of the wash pipe allows a top flapper to fall to a closed position. This flapper prevents flow from uphole to downhole thus allowing for well control with pressure applied to the flapper from the surface with the flapper on its seat. Thus the low pressure rating of the float shoe and its check valves is removed as a problem because the assembly of the flappers and the high pressure packer provide the needed high pressure barriers. Those skilled in the art will appreciate these and other aspects of the invention from a review of the description of the preferred embodiment and the associated drawings while appreciating that the full scope of the invention is to be determined from the appended claims.